Various attempts to recover liquid hydrocarbons (oil, kerogen, for example) from geological deposits (oil shale, oil sand, tar sand for example) over the past century have been commercially unsuccessful. One method was to mine and transport the shale to a processing facility, and heat the shale to about 500° C. while adding hydrogen. Energy recovery was inefficient and waste disposal was substantial.
More recently, systems and methods have been devised for down-well heating and extraction of liquid hydrocarbons from oil shale. Lengthy in-ground heat exchanger pipes with electric heating elements heat the oil shale to very high temperatures to drive the hydrocarbons toward another well where they are extracted. A major problem appears to be localized “hot spots” (generally caused by variations in geological formations) that quickly burn out the electric heating elements in the conventional heat exchanger pipe. Devices and methods are needed to mitigate hot spots and to provide more efficient heat transfer from a heater to a subterranean earth (soil or geologic formation, for example). Another potential application of such a device would be in situ remediation of organic-contaminated soils and geologic formations by thermal decomposition.
Specifically referenced and incorporated herein by reference in their entirety are the following U.S. patents:
U.S. Pat. No. 5,782,301 issued on Jul. 21, 1998 to Neuroth et al. entitled “Oil Well Heater Cable ”
U.S. Pat. No. 5,784,530 issued on Jul. 21, 1998 to Bridges entitled “Iterated Electrodes for Oil Wells”.
U.S. Pat. No. 6,353,706 issued on Mar. 5, 2002 to Bridges entitled “Optimum Oil-Well Casing Heating”.
U.S. Pat. No. 6,742,593 issued on Jun. 1, 2004 to Vinegar et al. entitled “In Situ Thermal Processing of a Hydrocarbon Containing Formation Using Heat Transfer from a Heat Transfer Fluid to Heat the Formation”.
U.S. Pat. No. 6,902,004 issued on Jun. 7, 2005 to De Rouffignac et al. entitled “In Situ Thermal Processing of a Hydrocarbon Containing Formation Using a Movable Heating Element”.
U.S. Pat. No. 6,929,067 issued on Aug. 16, 2005 to Vinegar et al. entitled “Heat Sources with Conductive Material for In Situ Thermal Processing of an Oil Shale Formation”.
U.S. Pat. No. 7,004,247 issued on Feb. 28, 2006 to Cole et al. entitled “Conductor-In-Conduit Heat Sources for In Situ Thermal Processing of an Oil Shale Formation”.
U.S. Pat. No. 7,056,422 issued on Jun. 6, 2006 to Dell'Orfano entitled “Batch Thermolytic Distillation of Carbonaceous Material”.
Also referenced as additional background material, but not incorporated herein is Great Britain Pat. No. 2,409,707 issued on Jun. 7, 2005 to Noel Alfred Warner entitled “Liquid Metal Heat Recovery in a Gas turbine Power System”.